1. Field of the Invention
This invention relates to: a device for sustained release of optical clearing agent which is used for giving an optical clearing agent to a diseased region on a luminal wall surface of a living body for example; an endoscope having the same; and an instrument for endoscopic surgery having the same.
2. Description of the Related Art
Conventional problems in endoscopic treatments which ESD (Endoscopic submucosal dissection) represents include intraoperative bleeding and postoperative bleeding.
However, an optical clearing agent capable of improving the light transmittancy for living-body by reducing light scattering has been developed in recent years.
One example of optical clearing agents is an aqueous solution acquired by adding glycerol and surfactant to urea, and this aqueous solution is applied to a living tissue to penetrate into the living tissue and then makes a penetrated region of the living tissue transparent like a jelly. Besides, the region that is made transparent by the optical clearing agent can be returned into its original state in which the penetrated region is uncleared, again, by giving a saline or the like to the penetrated region.
Optical clearing agents have been conventionally applied mainly through drop or injection, as disclosed in Non Patent Literature, Journal of X-ray Science and Technology, Vol. 10, No. 3-4, p 167-176, 2002 or Asian Journal of Physics, Vol. 15, No. 1, p 1-14, 2006 for example.
In order to reduce the risks of intraoperative bleeding and postoperative bleeding, it is desired that an optical clearing agent is applied to a diseased region before or after surgery so that vascular visibility is improved.
By the way, it is characteristic of such an optical clearing agent to take predetermined time to penetrate into a living tissue so that time lag occurs until an optical clearing effect is obtained. As a result, the optical clearing agent has to be applied to a target region with the optical clearing agent remaining at the target region, until the enough optical clearing effect is obtained.
However, a target region to which an optical clearing agent should be applied does not necessarily exist in the gravity direction in a lumen.
As a result, in a method of applying an optical clearing agent to a target region through drop, it is difficult to apply the optical clearing agent to a target region existing in the opposite direction to the gravity direction while the optical clearing agent is being kept stably remaining at the target region.
On the other hand, an optical clearing agent can be made to remain at a target region in a method of applying an optical clearing agent to a target region through injection. However, the range of a region to which the optical clearing agent is applied is extremely localized. As a result, in the case where the range of a region to which the optical clearing agent has to be applied is wide in the method of applying the optical clearing agent to the target region through injection, it not only is difficult to apply the optical clearing agent to the whole range of the desired region from an injection point but also has a high invation for living tissue.
However, for example, Patent literature, Japanese Patent Kokai No. 2008-188212, offers an agent-applying instrument that is used with the aim of applying an anesthetic to nasal cavity. This agent-applying instrument can be used for applying an agent to a wide range of a diseased region with low invasion with the agent kept stably remaining at the diseased region.
The agent-applying instrument disclosed in Japanese Patent Kokai No. 2008-188212 includes: an elongated stick-shaped base components 51; a gas passage 52 running along the base component; a cylinder-shaped balloon 53 placed on the whole circumference of the outside surface of the base component 51 and communicating with the gas passage 52; and an agent-holding component 54 placed on the outside surface of the balloon 53 and containing an agent that is applied to the body cavity, as shown in FIG. 8. And, the agent-applying instrument disclosed in Patent literature 1 is configured to apply an anesthetic to a desired region by supplying air to the gas passage 52 with a gas-supplying instrument to inflate the balloon 53 so that the agent-holding component 54 presses on the inside surface of the desired region to come into contact with the desired region.